Heat exchanger

ABSTRACT

A heat exchanger having a shell with a closure flange and an inner tube with an adapter having a peripheral sealing surface. The shell has an inner beveled sealing surface and a seal ring is pressed against the peripheral sealing surface and the beveled sealing surface by a compression ring carried by the shell flange. A retaining ring also carried by the shell flange extends into a peripheral groove in the adapter to limit axial movement between the inner tube and the shell.

United States Patent [72] lnventors lI)ohIL$;iDraves [56] References m un |r Maurice R. Garrison. Hamburg; Edward J. UNITED STATES PATENTS skiba wm m a of, N Y 2,424 221 7/1947 Brown Jr. i. 165/143 X [2]] A pl. No. 855,857 2,449,052 9/1948 Brown Jr. i 165/143 X [22] Filed Sept. 8, 1969 3,018,090 1/1962 Kaase et al 165/143 [45] Paemed July 20,197] 3,249,153 5/1966 Hulland 165/143 X American Precision Industries'lnc. Buffalo, N.Y.

[73] Assignee [54]. HEAT EXCHANGER 9 Claims, 2 Drawing Figs.

Primary Examiner-Frederick L. Maltteson Assistant ExaminerTheophil W. Streule Attorney-Christel and Bean ABSTRACT: A heat exchanger having a shell with a closure flange and an inner tube with an adapter having a peripheral sealing surface. The shell has an inner beveled sealing surface and a seal ring is pressed against the peripheral sealing surface and the beveled sealing surface by a compression ring carried by the shell flange. A retaining ring also carried by the shell flange extends into a peripheral groove in the adapter to limit axial movement between the inner tube and the shell.

HEAT EXCHANGER BACKGROUND OF THE INVENTION This invention relates to heat exchangers, and more particu- 5 larly to connections for heat exchangers of the type having an outer tube or shell enclosing an inner tube or tube bundle.

These heat exchangers are subject to heat exchange fluids at different temperatures and often at relatively high pressures. A problem encountered in such heat exchangers is leakage at their connections due to the high pressures involved and the relative contraction and expansion of the inner tube with respect to the outer tube with variations in temperature. Some attempts have been made to solve this problem but the means employed have not been entirely satisfactory. For example, one approach has utilized coacting tapered surfaces. However, they must be aligned, and if any one surface is damaged and requires machining it must be done to all of them.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat exchanger connection which is simple and strong in construction, rugged and durable in use, low in cost, and which can be easily assembled and disassembled.

Another object of this invention is to provide heat exchanger connection means having improved pressure seal-' ing means for preventing fluid leakage while accommodating relative expansion and contraction of the inner and outer tubes.

A further object of the present invention is to provide a heat exchanger connection in which elastomeric sealing means can be employed as well as metal or other sealing material.

Still another object is to provide the foregoing in an arrangement which facilitates repair if any sealing surface becomes damaged.

The foregoing and other objects, advantages and characterizing features of the present invention will become clearly apparent from the ensuing detailed description of an illustrative embodiment thereof, taken together with the accompanying drawing wherein like reference numerals denote like parts throughout.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a view, partly in section and partly in side elevation, of a heat exchanger of this invention; and

FIG. 2 is a vertical sectional view thereof taken about on lines 2-2 of FIG. 1.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now to the drawing, there is shown an illustrative heat exchanger of this invention comprising a pair of elongated, laterally spaced tubes and I2 terminating at one end thereof in a common flange 14 to which they are welded and which is connected to a return bend end cap 16 by suitable fasteners, such as stud bolts 18 and nuts 20 for example. The opposite ends of tubes 10 and 12 are welded to tubular members provided with radially outwardly projecting closure flanges 11 and 13. Tubes 10 and I2 and return bend end cap 16 form a generally hairpin-shaped shell, generally designated 22. A fluid inlet 24 is provided on tube 12 and a fluid outlet 26 is provided on tube 10, it being understood that the relative position of inlet and outlet can be reversed. The heat exchanger is supported by longitudinally spaced brackets 28 and, if desired, several heat exchangers can be connected together in series.

An inner, hairpin-shaped tube, generally designated 30, is enclosed by shell 22 in spaced relation thereto and comprises a pair of elongated straight'portions 32 and 34 connected together by a hairpin-shaped portion 36. As seen in FIG. I, inner tube 30 is formed in lengths and welded together as at 38 to form a unitary one-piece construction, the welded joints between portion 36 and portions 32 and 34 being disposed adjacent the juncture of end cap 116 and] shell tubes 10 and 12. End cap 16 is easily separated by removing studs 18 and nuts 20 to provide access to the hairpin portion of tube 30 for inspccting welds 38 and for ease of removal of tube 30 as will be described.

Inner tube 30 has an outlet end 40 and an inlet end 42, each connected to conduits (not shown) by suitable coupling means, generally designated 44. Since both couplings are identical, a detailed description of one will suffice. A sleeve 46 is welded or otherwise fixedly secured. to the inlet end 40 of inner tube 30 and is externally threaded as shown at 48. The free end of sleeve 46 has an inner conical seating surface 50 for receiving a complimentary outer conical seating surface 52 of a sleeve 54 adapted to receive the free end of a fluid conduit (not shown). An outer sleeve coupling member 56 has an internally threaded portion 58 engaging sleeve 46 and an inwardly directed flange 60 defining a shoulder 62. Sleeve 54 is provided with a peripheral flange 64 adapted to be engaged by shoulder 62 whereby axial inward movement of shoulder 62 urges seating surface 52 into contact with seating surface 50 of sleeve 46. The heat exchange fluid flowing through inner tube 30 can either be a coolant or a high temperature fluid, dependent on the heat transfer process desired.

The space between the inner wall of shell 22 and the outer wall of inner tube 30 defines an annular fluid passage 66 communicating with inlet 24 and outlet 26. Extending radially outwardly from the outer wall of tube 30 into passage 66 are a series of flat fins 68 elongated longitudinally of straight portions 32 and 34. As is known in the art, fins 68 increase the surface area exposed to the fluid in passage 66 and facilitate the heat exchange process. Fins 68 are in the form of generally U- shaped channels having web portions 70 welded or otherwise fixedly secured to the outer wall of tube 30 and opposite legs projecting radially from tube 30. This particular type of fin construction is known, and other fin constructions or no fins can be employed, if desired, within the purview of this invention.

Due to contraction and expansion of the materials of which shell 22 and tube 30 are formed, a certain amount of longitudinal movement of tube 30 relative to shell 22 is inherent. In accordance with this invention, enclosure connection means are provided adjacent flanges-ll and 13 of shell 22 for accommodating such relative axial movement within preselected limits while providing sealing pressure between shell 22 and tube 30. Since both such means are identical, only one is described in detail.

Such means comprises a generally cylindrical adapter body 72 welded or otherwise fixedly secured to tube 30 forming a flange thereabout and having a cylindrical peripheral sealing surface 74 with a circumferential groove 76 formed therein. The outer diameter of adapter 72 is less than the inner diameter of shell tubes 10, 12. An annular compression ring 78 of an internal diameter greater than adapter 76 and approximately that of the shell tubes has one face 80 thereof in abutting engagement with flange 13 and the opposite face 82 in abutting engagement with a split retainer ring 84. Ring 78 and ring 84 are secured to closure flange 13 by a plurality of studs 86 extending through rings 78, 84 and flange 113 and having nuts 88 threaded on the free ends thereof. The inner portion 90 of ring 84 extends into groove 76 and is thinner than the groove width to permit limited longitudinal movement of tube 30 in direction of return bend cap 16.

Flange 13 is inclined inwardly adjacent the inner wall of shell 22 to provide a beveled sealing surface 94. A continuous seal ring 96 encircles the peripheral sealing surface 74 of flange 72 and is adapted to contact face 80 of compression ring 78 and beveled sealing surface 94 of flange 13. Thus, when bolts 86 are drawn tight, the axial force transmitted through ring 84 and ring 78 compresses seal 96 into pressure sealing engagement with sealing surfaces 74 and 94. Seal 96 can be formed of a suitable ductile ferrous or nonferrous metal, such as soft iron or copper, or of a plastic material, depending on the conditions of use. A significant feature of this invention is that a resiliently yieldable, elastomeric seal, such as rubber, neoprene or other material also can be used for seal 96 in low temperature applications. This is especially advantageous in that only a minimum of force is required to effect an efficient leak-proof seal while permitting longitudinal movement of tube 30-relative to shell 22.

In use, heat exchange fluid is admitted into inlet 40 of tube 30 and conveyed therethrough to outlet 42. The fluid to be heated or cooled, which can be a gas or liquid, is admitted into inlet 26 and circulated between shell 22 and inner tube 30 and finally discharged through outlet 24. The fluid to be treated contacts fins 68 during its flow thereby facilitating the heat exchange process. ln order to accommodate relative expansion and contraction between shell 22 and inner tube 30, relative longitudinal movement therebetween is permitted by the connection means between tube 30 and shell 22 hereinabove described and is limited only by the spacing between split ring 90 and the opposite sidewalls of groove 76. Seal 96 allows such axial movement while maintaining a fluidtight sealing pressure because of its sliding sealing engagement with surface 72.

Although the connection means of the present invention is illustrated, for convenience, only in a double pipe heat exchanger, it should be understood that it has utility in other types of heat exchangers. For example, a tube bundle can be used in lieu of the single inner tube 30 with the connection means of this invention disposed between the header end plates or flanges of the tube bundle and the shell. Reference to an inner tube in the claims contemplates a plurality or bundle of tubes as well as a single tube.

From the foregoing, it is apparent that the objects of the present invention have been fully accomplished. As a result of this invention, a simple and improved connection means for a heat exchanger is provided for effecting sealing pressure in a more efficient manner and accommodating longitudinal movement between relatively moving parts of the exchanger. Seal 96 is pressed against surfaces 74 and 94, in fluidtight relation, providing a sliding seal with surface 74. If that surface should become damaged, and require repair, it alone can be machined and seal 96 will still seal thereagainst. Similarly, if surface 94 is damaged and requires machining, its repair will not affect surface 74 and the action of seal 96. The sealing surfaces 74, 94 are not aligned in a manner requiring adjustment of one upon reasonable repair of the other.

Also, the connection means permits easy dismantling and removal of the inner tube or tube bundle from the shell. Bolts 86 are removed, permitting removal of retaining rings 84. Couplings 44 are separated and end cap 16 is detached, whereupon inner tube 30 can be withdrawn from shell 22. It is not necessary to remove tube manifold or piping connections to remove the inner tube from the shell or casing. In addition, elastomer seals can be employed with the connection means of this invention thereby requiring less compressive forces to be exerted thereon and also permitting more liberal tolerances on the seal seating surfaces.

A preferred embodiment of this invention having been disclosed in detail, it is to be understood that this has been done by way ofillustration only.

We claim:

1. In a heat exchanger comprising a shell having closure flange and an inner tube disposed within said shell in spaced relation thereto, means for connecting said inner tube to said shell in fluidtight relation and for longitudinal movement relative thereto; said connecting means comprising means on said inner tube providing an outer peripheral sealing surface, said shell having an internal wall with a beveled sealing surface adjacent said peripheral sealing surface, an annular compression member carried by said shell flange; and a seal ring encircling said inner tube and interposed between said peripheral sealing surface, said beveled sealing surface, and said annular member, whereby an axial force exerted on said annular member compresses said seal ring into pressure sealing engagement with said peripheral sealing surface and said beveled sealin surface.

2. 1% heat exchanger according to claim 1 wherein said connecting means includes means limiting longitudinal movement between said inner tube and said shell.

3. A heat exchanger according to claim 1 wherein said means on said inner tube providing said peripheral sealing sur face comprises an adapter provided with a circumferential groove; said connecting means also including a retainer ring carried by said shell flange and having a portion extending into said groove.

4. A heat exchanger according to claim 3, including means releasably securing said retainer ring and said compression ring to said flange and for compressing said seal ring against both said sealing surfaces.

5. A heat exchanger according to claim 4 wherein said peripheral sealing surface is a cylindrical surface having an outer diameter smaller than the inner diameter of said shell, whereby said inner tube and said adapter can be drawn through said shell upon removing said retainer ring, said compression ring having an inner diameter larger than the outer diameter of said adapter.

6. A heat exchanger as set forth in claim 5, said retainer ring comprising a split ring having an inner diameter smaller than the outer diameter of said adapter.

7. A heat exchanger as set forth in claim 5, said beveled surface being provided at the inner periphery of said flange.

8. A heat exchanger according to claim 1 wherein said seal is formed ofa ductile metal.

9. A heat exchanger according to claim 1 wherein said seal is formed of an elastomer material.

Disclaimer 3,593,782.J0im G. Dm ves, Dunkirk Maurice R. Garrison, Hamburg, and Edward J. Slciba, Williamsvilie, N.Y. HEAT EXCHANGER. Patent dated July 20, 1971. Disclaimer filed Apr. 12, 1972, by the assignee, Robert O. H agner. Hereby enters this disclaimer to claims 1, 8 and 9 of said patent.

[Oyficial Gazette June 27', [972.] 

2. A heat exchanger according to claim 1 wherein said connecting means includes means limiting longitudinal movement between said inner tube and said shell.
 3. A heat exchanger according to claim 1 wherein said means on said inner tube providing said peripheral sealing surface comprises an adapter provided with a circumferential groove; said connecting means also including a retainer ring carried by said shell flange and having a portion extending into said groove.
 4. A heat exchanger according to claim 3, including means releasably securing said retainer ring and said compression ring to said flange and for compressing said seal ring against both said sealing surfaces.
 5. A heat exchanger according to claim 4 wherein said peripheral sealing surface is a cylindrical surface having an outer diameter smaller than the inner diameter of said shell, whereby said inner tube and said adapter can be drawn through said shell upon removing said retainer ring, said compression ring having an inner diameter larger than the outer diameter of said adapter.
 6. A heat exchanger as set forth in claim 5, said retainer ring comprising a split ring having an inner diameter smaller than the outer diameter of said adapter.
 7. A heat exchanger as set forth in claim 5, said beveled surface being provided at the inner periphery of said flange.
 8. A heat exchanger according to claim 1 wherein said seal is formed of a ductile metal.
 9. A heat exchanger according to claim 1 wherein said seal is formed of an elastomer material. 